The present invention relates to an optical sensor head for the directional detecting of optical radiation, having an arrangement of individual optical systems which are differently sloped with their optical axes, are convergently aligned in the viewing direction and each have conical partially overlapping viewing areas.
Known sensor heads of this type (German Patent Document DE 37 36 616 C1), whose optical axes are aligned to be convergent with an intersecting point which is situated in front of the light entrance openings of the individual optical systems, have considerable constructive advantages in comparison to those sensor heads with a rearwardly converging axis geometry. This is mainly because they permit a flat construction of the sensor head and an extremely close positioning of the light entrance openings on the forward sensor head surfaces. These sensor head however are unsuitable for applications in which a precise bounding of the observation field of the sensor head to a defined angular area is required. This is the case, for example, when for a circumferential observation, several sensor heads are provided which are each aligned with different observation sectors. It must not only be ensured that each observation sector is controlled without gaps only by the sensor head assigned to it but that any overlapping at the sector boundaries, which make a clear determination of the direction of the optical radiation which is incident in this area difficult or impossible, must be avoided.
It is an object of the invention to provide a sensor head of the above-described type so that, while a simple method of construction and operation is maintained, a precise bounding of a given angular area is ensured.
This and other objects are achieved by the present invention which provides an optical sensor head for directional detecting of optical radiation, comprising an arrangement of individual optical systems that have optical axes that are differently sloped, are convergently aligned in a viewing direction and have conical partially overlapping viewing areas. The individual optical systems include at least one outer-edge-side individual optical system and at least one neighboring optical system situated closer to a sensor center and having a light entrance opening. A beam diaphragm partially shades the viewing cone of the outer-edge-side individual optical system to create a diaphragm-bounded edge beam of the outer-edge-side individual optical system. The neighboring optical system is arranged with its light entrance opening approximately at the level of the diaphragm-bounded edge beams of the outer-edge-side individual optical system.
The present invention is based on the recognition that an angularly precise bounding of the observation range of the sensor head cannot be achieved merely by partial shading of the individual optical systems on the exterior edge. Rather, with surprisingly low constructional expenditures, the precise bounding is achieved by a combination of such a shading with the raising of the individual optical systems situated farther on the inside, without any disturbing effect on the operability of the sensor head in the thus limited observation sector. The sensor head according to the invention is especially well-suited for the above-described application in which, for ensuring a clear angle detection of the received optical radiation, any disturbing overlapping across boundaries between adjacent observation sectors, which are each controlled by a sensor head, must be prevented.
In a particularly preferred embodiment of the invention, the optical axis of the neighboring optical system(s) which is situated farther toward the inside, taking into account the viewing cone opening angle, is sloped in such a manner that the lower edge beams of the viewing cone, without any diaphragm bounding extend essentially at the same slope as the edge beams of the individual optical system on the side of the outer edge of the sensor head which are bounded by the diaphragm. Thus, the viewing range of the neighboring optical system(s), because of the arrangement of the diaphragm, is essentially maintained in an unlimited manner.
In certain embodiments that are particularly advantageous with respect to installation, the beam diaphragm is preferably arranged outside the sensor head surface occupied by the individual optical systems so that it can be accommodated on the sensor head without any problems and without interfering with the narrow mutual positioning of the light entrance openings on the forward sensor head surface.
For continuous covering of the observation sector with as few individual optical systems as possible which are uniformly distributed with their viewing cones, in certain embodiments the viewing cone of the outer-edge-side individual optical system is shaded by means of the diaphragm arrangement up to the optical axis.
For a protection against interfering reflexes and/or beam scattering, the beam diaphragm in certain embodiments expediently has a reflection-reducing surface structure. To this end, certain embodiments have a saw-tooth structure and/or a radiation-absorbing surface coating.
In certain embodiments, an axis geometry which constructionally and operationally is particularly preferred for the monitoring of the diaphragm-bounded observation sector has the optical axes of the individual optical systems centrically aligned with the center axis of the sensor head.
In certain embodiments of the invention, the individual optical systems are connected via optical fibers with an optoelectrical converter which feeds the directional receiving signals to an electronic analyzing circuit for angle detection.
In certain embodiments, the diaphragm-bounded viewing area of the sensor head extends along a spatial angle of 90.degree. so that an azimuthal full-circle observation can be achieved by means of four sensor heads which bound on one another without overlapping.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.